This invention relates to adhesive dispensing systems of the type used for applying adhesive to a set of sheets that are to be bound together into a booklet.
It is known to bind together sheets of a booklet by applying adhesive to the edge of a set of sheets. This is disclosed, for example, in U.S. Pat. No. 4,009,071 entitled SHEET BINDING APPARATUS which issued on Feb. 22, 1977 in the names of Snellman et al. In accordance with the disclosure and the Snellman et al patent, sets of sheets are formed in a sorter/collator or the like and jogged to align the sheet edges. Then glue is applied to an endless belt and the belt is moved into engagement with edges of the sheets in the various compartments of the sorter, collator or the like to deposit glue on the edges of the sets of sheets. The Snellman et al patent discloses a control system for operation of the sheet binding apparatus. Similar disclosures of binding apparatus are found in U.S. Pat. Nos. 4,077,831; 4,116,750; and 4,145,241.
U.S. Pat. No. 3,404,880 issued on Oct. 8, 1968 in the names of H. R. Porter, Jr. et al for a GLUING ATTACHMENT FOR A COLLATING MACHINE. The apparatus disclosed in the Porter Jr. et al patent comprises a collator which holds stacks of sheets adjacent to a conveyor, and sheet transfer means which transfers individual sheets onto the conveyor. As each sheet is lifted from the stack and placed on the conveyor a small spot of glue is applied to the sheet so that when the sheets are assembled into a booklet the glue is effective to hold the sheets together.
U.S. Pat. No. 3,908,869 entitled METHOD AND APPARATUS FOR DISPENSING AIR-CURABLE VISCUS MATERIALS, which issued on Sept. 30, 1975 in the name of W. A. Little, discloses formation of a gasket by dispensing a rubber-like material through a nozzle that is driven in a path over a support for the gasket. The rubber-like material is delivered from a container to the nozzle through a dispensing system comprising a pump and a pressure accumulator. Apparatus is disclosed for preventing drying out or clogging of the rubber-like material in the nozzle.
It is also known to pressurize containers of liquid to force the flow of liquid out of the container in response to opening of a valve at a remote location. For example, U.S. Pat. No. 3,228,413 to Stevens shows a device for tapping a keg of beer wherein a passageway permits pressurized gas to enter the beer keg and beer can flow from the pressurized keg through a second passage and then through a valve into a glass or other container.
Certain problems are presented by automated sheet binding apparatus used for producing booklets in an on-line binding apparatus and method as disclosed in the beforementioned U.S. Pat. application Ser. no. 380,966 entitled BINDING APPARATUS AND METHOD. For example, such binding apparatus and method can receive sets of sheets wherein the sheets are fed seriatim from a copier/duplicator or the like and delivered directly to the binding apparatus. The individual sheets must be quickly fed through the binder, have adhesive applied thereto, assembled into sets with the adhesive between adjacent sheets, and a completed booklet discharged to a tote tray so that sheets of another set can immediately be received for forming another booklet. In addition, such apparatus may be operated by persons with very little training; thus it is desireable that the apparatus be essentially automatic in its operation. At the same time, it is important for the operator to be signaled in the event there is an inadequate supply of adhesive, in the event adhesive is not being dispensed onto sheets of paper as required, and to signal the operator in the event an overflow container adapted to receive excess adhesive becomes full. Moreover, it is important that the adhesive dispensing system for such binding apparatus and method be at least partially self-testing and, to some extent, even be self-correcting. This avoids the need for expensive and time consuming service calls and also avoids unproductive downtime for the apparatus.